Antaritica and Alaska are different. The wildlife is different, the scenrey is different, the culture and history of the lands are so different( I am not even sure there is a" culture " in Antaritica as I assume it is basically uninhabitated) so as for you being disappointed, it is up to you.
Go to Alaska with the expectations of seeing something " different" form Antaritica and you will have a great time.
The cruise along the west coast of Canada and Alaska is so beautiful, I can't imagine trying to compare the experiences!
I bet the ice bergs were beautiful( awesome in fact) in Antartica, and I'd love to see it, but I know it wouldn't be the same as the Coastal Mountain rainforests of the Pacific Northwest!